Vertically integrated 3-axis MEMS angular accelerometer with integrated electronics

- Invensense, Inc.

Sensors for measuring angular acceleration about three mutually orthogonal axes, X, Y, Z or about the combination of these axes are disclosed. The sensor comprises a sensor subassembly. The sensor subassembly further comprises a base which is substantially parallel to the X-Y sensing plane; a proof mass disposed in the X-Y sensing plane and constrained to rotate substantially about the X, and/or Y, and/or Z, by at least one linkage and is responsive to angular accelerations about the X, and/or Y, and/or Z directions. Finally, the sensor includes at least one electrode at the base plate or perpendicular to the base plate and at least one transducer for each sensing direction of the sensor subassembly responsive to the angular acceleration. Multi-axis detection is enabled by adjusting a configuration of flexures and electrodes.

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Description
FIELD OF THE INVENTION

The present invention relates generally to accelerometers and more specifically to multi axis accelerometers that sense angular (rotational) accelerations.

BACKGROUND OF THE INVENTION

Angular or rotational accelerometers are used to measure rotational acceleration about a specific axis. Rotational accelerometers have many applications such as vehicle rollover event prevention, rotational vibration suppression for hard disk drives, airbag deployment and so on. With the advances in MEMS technology various rotational accelerometers that can be fabricated using silicon micromachining techniques have been proposed in U.S. Pat. No. 5,251,484, “Rotational accelerometer,” Oct. 12, 1993; U.S. Pat. No. 6,718,826, “Balanced angular accelerometer,” Apr. 13, 2004; U.S. Pat. No. 5,872,313, Temperature-compensated surface micromachined angular rate sensor,” Feb. 16, 1999; U.S. Pat. No. 6,257,062, “Angular accelerometer,” Jul. 10, 2001. In these applications surface micromachining used to fabricate the moving proof masses. Surface micromachining imposes limits on the structures. For example, the proof mass thickness is limited to the thickness of the deposited films. Surface micromachining also suffers for the stiction problem as a result of sacrificial etching and wet release processes. Therefore proof masses fabricated using this method requires additional supports around the perimeter of the proof mass to reduce stiction and to increase the stability. This results in relatively more complicated devices and stringent requirements for the fabrication of additional springs that would not disturb the operation of the rotational accelerometer. On the other hand bulk micromachining overcomes most of the problems associated with the surface micromachining. U.S. Pat. No. 7,077,007, “Deep reactive ion etching process and microelectromechanical devices formed thereby,” Jul. 18, 1006 describes DRIE etching for bulk micromachined angular accelerometers.

The sensing methods used in MEMS accelerometer vary. Capacitive sensors provide high performance as well as low cost. Because of these features it became the method of choice for most of the consumer market applications. But to be able to obtain high sensitivity and low noise floor the parasitic capacitances need to be reduced or eliminated. This can be achieved by integrating MEMS and electronics. The accelerometers described in the above-identified patents are not integrated with the detection electronics. In a typical system, the detection electronics needs to be connected to the MEMS substrate through wire bonding. Accordingly, this system suffers from increased parasitics and is susceptible to noise and coupling of unwanted signals.

Therefore, there is a need for rotational accelerometers that are fabricated using bulk micromachining methods and integrated with electronics. There is also need for multi-axis accelerometers that are insensitive to linear accelerations. The present invention addresses such needs.

SUMMARY OF THE INVENTION

Sensors for measuring angular acceleration about three mutually orthogonal axes, X, Y, Z or about the combination of these axes are disclosed. The angular accelerometers are fabricated by bulk micromachining and integrated with electronics. The sensor comprises a sensor subassembly. The sensor subassembly further comprises a base which is substantially parallel to the X-Y sensing plane; a proof mass disposed in the X-Y sensing plane and constrained to move substantially about the X, and/or Y, and/or Z, by at least one linkage and is responsive to angular accelerations about the X, and/or Y, and/or Z directions. Finally, the sensor includes at least one electrode at the base plate or perpendicular to the base plate and at least one transducer for each sensing direction of the sensor subassembly responsive to the angular acceleration. Multi-axis detection is enabled by adjusting a configuration of flexures and electrodes.

Two structures or more can be used per axis to enable full bridge measurements to further reduce the susceptibility to power supply changes, cross axis coupling and the complexity of the sense electronics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows top view of a portion of a MEMS assembly according to an embodiment.

FIG. 1B shows the cross section AA′ of the angular accelerometer in FIG. 1A.

FIG. 1C shows an angular accelerometer comprising two proof masses.

FIG. 1D shows the detection electronics for the accelerometer shown in FIG. 1C.

FIG. 2A illustrates an angular accelerometer composed of two proof masses.

FIG. 2B shows an alternative arrangement of proof masses shown in FIG. 2A.

FIG. 3A illustrates multi-axis accelerometer (X and Z rotational accelerometer, Z linear accelerometer).

FIG. 3B illustrates the cross section of the accelerometer shown in FIG. 3A and the proof mass deflection as a function of input rotational X and linear Z acceleration.

FIG. 3C illustrates one proof mass that is sensitive to rotational X and Z accelerations but insensitive to linear accelerations.

FIG. 4A illustrates four axis accelerometer (X, Y and Z rotational, Z linear accelerometer).

FIG. 4B illustrates an alternative arrangement of proof masses shown in FIG. 4A.

FIG. 4C shows the detection electronics for the Z-axis angular accelerometers shown in FIGS. 4A and 4B.

FIG. 5 illustrates one variation of flexures.

 DETAILED DESCRIPTION

The present invention relates generally to motion sensing devices and more specifically to angular accelerometers utilized in integrated circuits. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.

A method and system in accordance with the present invention relates to the accelerometers that are fabricated using silicon micromachining methods that have been described in U.S. Pat. No. 7,104,129, entitled “Vertically Integrated MEMS Structure with Electronics in a Hermetically Sealed Cavity,”, issued Sep. 12, 2006, and assigned to the assignee of the present application; and U.S. Pat. No. 7,247,246, entitled “Vertical Integration of a MEMS Structure with Electronics in a Hermetically Sealed Cavity,” issued Jul. 24, 2007, and assigned to the assignee of the present application, both of which are incorporated by reference in their entirety herein. The assembly approach (Nasiri fabrication process) described in the said patents provides a cost effective means to simultaneously protect the movable sensing element and to integrate the low noise electronics. The electronic circuitry is fabricated on a dedicated electronics silicon substrate. The MEMS assembly then bonded on the electronic or sense substrate using a metal bonding technique using a low temperature process that does not damage or compromise the electronic circuitry. A plurality of transducers is assembled in this manner at the wafer level where hundreds to thousands are produced simultaneously. A small size form factor is achieved by the vertical integration of the sensing element with its sensing circuit. Other patents that are relevant for accelerometer fabrication are: U.S. Pat. No. 6,939,473 “Method of making an X-Y axis dual-mass tuning fork gyroscope with vertically integrated electronics and wafer-scale hermetic packaging”; U.S. Pat. No. 7,258,011 “Multiple axis accelerometer”; and U.S. Pat. No. 7,250,353 “Method and system of releasing a MEMS structure” assigned to the assignee of the present application.

FIGS. 1A and 1B show a rotational accelerometer 100 and the cross section AA of the accelerator 100, respectively. As is seen, a proof mass 102 is attached to the cover plate 104 at a single anchor 106 through flexural springs 108. The anchor 106 is at the center of the proof mass 102. The proof mass 102 is movable. It is constraint to rotate along Z axis which is perpendicular to the proof mass 102. The springs 108 can be made in any shape to adjust the spring constant. The anchor 106 is attached to the cover plate 104 utilizing a bonding process such as fusion bonding. The anchor 106 is also connected to the sense substrate 118 through an electrical connection 112.

The electrical connection 112 can be made under the anchor 106 as described in published U.S. Published Application No. 2006/0208326, entitled “Method of fabrication of al/ge bonding in a wafer packaging environment and a product produced therefrom” which is also assigned to the assignee of the present application. The method described in that published patent application allows making mechanical and electrical connections on the same anchor. The single anchoring of the proof mass 102 reduces the stresses that may be induced by the package warpage. The sense electrodes 114a and 114b are coupled to sensor substrate 118 and do not move with respect to proof mass. When the proof mass 102 is subjected to an angular acceleration about the axis (Z-axis) perpendicular to the plane, the forces acting on the proof mass 102 rotates it about the anchor 106. The rotation of the proof mass 102 is sensed capacitively. The moving electrodes 116 extending from the proof mass 102 form capacitors with the sense electrodes 114.

The sense electrodes 114a-114b are bonded to the cover plate 104 and electrically connected to the sense substrate 118. There are two sense electrodes 114a-114b per each moving electrode 116 on the proof mass 102 forming two capacitors. The value of one of these capacitors increases, whereas the value of other one decreases as the proof mass 102 rotates. The capacitors are labeled CCW 120 and CCCW 122 as shown in FIG. 1A.

CCW 120 increases if the proof mass 102 rotates in clock wise direction and CCCW 122 increases if the proof mass 102 rotates in the counter-clockwise direction about the axis perpendicular to the sense substrate. CCW 120 and CCCW 122 allow for the differential detection of the proof mass 102 rotation and hence provide an indication of the angular acceleration.

Referring to FIG. 1A, the accelerometer 100 has features to provide reliable operation. For example, it has motion stoppers 124a-124b about Z rotation to restrict the motion for excessive acceleration. In the directions that are out of plane, its stiffness is high enough to provide mechanical stability. The accelerometer 100 has also self test electrodes 126 to actuate the proof mass 102 for test purposes.

As before mentioned, FIG. 1B shows the cross section of the angular accelerometer shown in FIG. 1A. Other MEMS devices such as accelerometers and gyros have been disclosed previously by the assignee of the present application (U.S. Pat. No. 7,258,011, “Multiple axis accelerometer”; U.S. Pat. No. 6,939,473, “Method of making an X-Y axis dual-mass tuning fork gyroscope with vertically integrated electronics and wafer-scale hermetic packaging”; U.S. Pat. No. 6,892,575, “X-Y axis dual-mass tuning fork gyroscope with vertically integrated electronics and wafer-scale hermetic packaging”). A similar fabrication platform described in these patents may also be used for the angular accelerometers shown in FIG. 1B.

The fabrication process starts with the manufacturing of the cover plate 104. First alignment marks are patterned on top of the cap or cover wafer. These marks will be later used to align the cover wafer to the sense substrate. Then the cover plate 104 is oxidized preferably using thermal oxidation to form an oxide layer. The preferable thickness of the oxide is between 0.5 and 1 micron. The oxide is patterned using lithographic methods to define the cavities in the cover plate 104.

The cavity depth can be further increased by etching the exposed silicon surfaces in the cover plate 104. But, if the structures in the actuator layer are not supposed to move more than the oxide thickness in vertical direction or there are no difficulties associated with having a cover in the close proximity of the moving parts, the silicon etch step may be skipped.

Then, the cover plate 104 is cleaned and bonded to another low total thickness variation wafer. The second wafer will form an actuator layer after thinning it down to preferably 40 microns. The actuator layer includes the proof mass 102 the sense electrodes 114a and 114b and the flexure springs 108 any other structures such as self test electrodes and over travel stoppers. The next step in the process is the formation of the stand offs. An etch, such as an KOH etch, is suitable for this step. The height of the stand offs determine the vertical separation between actuator layer and the sense substrate 118. If there are electrodes on the sense substrate 118, this gap also determines the sensing capacitor gaps. Then, a germanium (Ge) layer is deposited and patterned. In the next step, elements of the rotational accelerometer are defined lithographically and etched using DRIE in the actuator layer. In the final step, the actuator layer is bonded a sense substrate using eutectic bonding.

Accordingly, as is seen in FIG. 1B, the active areas of the sense substrate 118 include regions that will make electrical contact with an actuator layer where the angular accelerometer 100 is defined, as well as circuitry 125 for sensing output signals from the angular accelerometer 100. Such circuitry 125 is preferably conventional CMOS circuitry. The top layer 127 of metal deposited in the conventional CMOS process is suitable for use as a bond metal. This upper layer 127 of metal defines bond pads for the connections to the sense electrodes 114a and 114b and the proof masses 102. One can also put electrodes on the top layer 127 to measure out of plane motion of the accelerometer in the case X and Y angular accelerometer.

The connections to the proof masses 102 and sense electrodes 114a and 114b can be routed in the lower CMOS metals 129, 131 and 133 where metals can cross over each other in different layers. This allows for complicated routing schemes to be utilized for connecting the MEMS device to the active electronics. Another advantage of having the sense substrate 118 in the close proximity of the angular accelerometer is that the connections between the MEMS device and sense electronics can be made very short. This reduces the parasitic coupling to ground, cross coupling between the wires and EMI coupling.

The above-described fabrication process produces hermetically sealed sensors for example utilizing sealing rings 135. The sense substrate 118 is preferably attached to the actuator layer via a metal-to-metal bond, which can be made hermetic. Likewise, the actuator layer is preferably attached to cover plate 104 by a fusion bond, which can also be made hermetic. As a result, the entire assembly of sense substrate 118, actuator layer and cover plate 104 can provide a hermetic barrier between angular accelerometer elements and an ambient environment. The pressure in the cavity can be adjusted during the eutectic bonding process. This allows the quality factor of the angular accelerometer to be controlled for better noise performance and dynamic response.

The above-described fabrication process also allows combining various inertial measurement devices on the same substrate. The angular accelerometers described in this patent can be easily integrated with linear accelerometers as well as low cost gyroscopes.

One can use two of the structures shown in FIG. 1A to provide four changing capacitances as shown in FIG. 1C. Note that, in this case the proof masses are electrically isolated. This allows for the detection of a capacitance change utilizing a full bridge configuration in so doing common mode signals are eliminated and allows using simpler electronics can be utilized. The capacitance change of the accelerometers described above can be detected by various circuits.

An example of circuitry for detecting the capacitance change due to rotational acceleration is shown in FIG. 1D where a full bridge configuration is utilized. As is seen, AC voltages 201a, 201b, which are 180 degree out of phase with respect to each other are applied to the proof masses 202a and 202b. The output voltage is detected off the sense electrodes utilizing an operational amplifier 204. When there is no acceleration, the bridge is in balanced and the output voltage is zero. Angular acceleration of the proof masses 202a and 202b disturbs the balance and gives rise to an AC voltage at the operational amplifier 204 output which amplitude is proportional to the acceleration. The operational amplifier 204 output later can be demodulated to obtain a signal directly proportional to the acceleration.

In this embodiment, a full bridge circuit is described but one of ordinary skill in the art readily recognizes other means of capacitive detection such as pseudo bridge, half bridge can also be employed. Alternatively, one can also drive the sense electrodes and monitor the proof mass motion and by observing the output voltages of the op-amp.

In an alternative configuration to obtain full bridge configuration, instead of using the full circular proof mass of FIG. 1A, one can use only half of the proof mass 302-304. This reduces the area usage as shown in FIG. 2A at the expense of sensitivity. Each proof mass 302-304 is connected to a single anchor point by three or more flexures. In this case CCW1 306 and CCW2 308 increase with the clock wise rotation of the proof mass 302 and 304 whereas CCCW1 310 and CCCW2 312 decrease. The change in the capacitance can be detected in a full bridge configuration as shown in FIG. 1D. FIG. 2B shows an alternative placement for the proof masses of FIG. 2A.

In another configuration as shown in FIG. 3A, the flexures can be configured such that the proof masses 402′ and 404′ become sensitive to rotation about another axis (X) in addition to the first rotational axis which is Z in this case. The Z-rotation detection method is same as the scheme described in FIG. 2. However, attaching the proof masses 402 and 404 with flexures along the edge of the half circle makes them sensitive to the rotations about the axis parallel to that edge. For Z axis rotation, the flexures simply flex allowing the rotation of the proof mass 402 and 404. For X axis rotation, the flexures make a torsional motion. The out of plane motion of the proof masses 402 and 404 can be measured by parallel plate capacitors between the proof masses 402 and 404 and the sense substrate.

In FIG. 3A, the capacitance between the proof mass 402 and the substrate is CPM1 414 and the other capacitor is CPM2 416 which is between the proof mass 404 and sense substrate. The rotational acceleration about X moves one of the proof masses away from the substrate and the other one closer to the substrate. This increases the capacitance CPM2 416′ and reduces the CPM1 414′ according to FIG. 3B. These two capacitors can be used for differential detection of the rotation. Again, by replicating the structure shown in FIG. 3A, one can obtain four capacitances for X axis rotation to implement full bridge detection. However, for Z rotation, one structure as shown in FIG. 3A is enough to implement full bridge configuration, but two structure configuration also improves Z sensitivity. In addition to rotational accelerations, these accelerometers can be used to measure linear acceleration along Z direction as shown in FIG. 3B. In this case, the sum of the CPM1 414′ and CPM2 416′ needs to be detected, rather than the difference of them which is the case for measuring rotational acceleration about the X axis.

Alternatively, one can use the structure shown in FIG. 3C for X and Z rotation where X direction is in plane and parallel to the flexure 612 and Z direction is perpendicular to the lateral plane. In this structure, the two proof masses (402, 404) of FIG. 3A are combined to form a single proof mass 610. The proof mass 610 is constraint to rotate about the anchor 618 and about the flexure 612. Electrodes 602 and 604 are sensitive to rotations about Z. The electrodes 606 and 608 which are between the sense substrate and the proof mass 610 are sensitive to rotations about X. However, for this structure linear acceleration along Z direction will not result in any capacitance change on CPMP and CPMN therefore this accelerometer is insensitive to linear acceleration along Z. Full bridge configuration will require two of these structures.

FIG. 4A shows a three axis rotational accelerometer. There are four proof masses 702, 704, 706 and 708. The Z rotation is detected through CCW1 710, CCCW1 712, CCW2 722, CCCW2 724, CCW3 726, CCCW3 728, CCW4 730, and CCCW4 732 capacitors. One can easily construct full bridge configuration for this case as shown in FIG. 4C. Basically, proof mass 702 and 706 are connected in parallel likewise proof mass 704 and 708. The rotations about X and Y are sensed through capacitors CPM2 716, CPM4 720 and, CPM1 714, CPM3 718 respectively. When there is rotation about positive X direction, CPM2 716 increases and CPM4 720 decreases. Since the rotation axis is through the centers of CPM1 714 and CPM3 718 these capacitors do not change. Similarly, for Y axis rotation only CPM1 714 and CPM3 718 change, but CPM2 716 and CPM4 720 remain the same. The accelerometer shown in FIG. 4A also sensitive to Z axis linear accelerations. This acceleration can be detected by sensing the sum of CPM1 714, CPM2 716, CPM3 718 and CPM4 720. In an alternative configuration shown in FIG. 4C, the orientation of the proof masses are changed. Placing the X and Y axis rotation detection sensors away from the center of the device increases the sensitivity.

FIG. 5 shows an example of a proof mass 800 which includes a different type of flexure 802. One can use folded springs to tailor the spring constant. A folded spring can be connected to the proof mass at the center as shown in FIG. 5. This configuration allows obtaining small spring constants for increased sensitivity in small areas.

Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.

Claims

1. A rotational accelerometer comprising:

a cover substrate,
a sense substrate; and
an actuator layer; the actuator layer comprising at least two proof masses constrained to rotate about at least one axis, the at least two proof masses being anchored to the cover and to the sense substrate via at least one flexure, and a plurality of electrodes that can sense rotation about the at least one axis, capacitively, wherein at least one of the two proof masses is constrained to rotate about substantially a Z-direction to measure rotational acceleration about the Z-direction, and is constrained to rotate about substantially a X-direction to measure rotational acceleration about the X-direction and the other of the two proof masses is constrained to rotate about substantially Z-direction to measure rotational acceleration about the Z-direction, and is constrained to rotate about substantially a Y-direction to measure rotational acceleration about the Y-direction.

2. The accelerometer of claim 1 wherein the cover substrate and the sense substrate provide for a hermetically sealed controlled enclosure for the accelerometer.

3. The accelerometer of claim 1 wherein the at least one proof mass is constrained to rotate substantially about a Z-direction to measure rotational acceleration about the Z-direction, and is constrained to rotate about substantially for X-direction to measure rotational acceleration about the X-direction.

4. The accelerometer of claim 1 wherein the at least one proof mass is constrained to rotate substantially about a Z-direction to measure rotational acceleration about the Z-direction, and is constrained to rotate about substantially a Y-direction to measure rotational acceleration about the Y-direction.

5. The accelerometer of claim 1 wherein the plurality of electrodes form a parallel plate capacitance.

6. The accelerometer of claim 1 wherein a full bridge configuration is utilized for capacitive measurement of the at least two proof masses.

7. The accelerometer of claim 1, wherein a full bridge configuration is utilized for capacitance measurement of the at least two proof masses constrained to rotate about a Z-direction.

8. The accelerometer of claim 1, wherein a full bridge configuration is utilized for capacitance measurement of the at least two proof masses constrained to rotate about a Y-direction.

9. The accelerometer of claim 1, wherein a full bridge configuration is utilized for capacitance measurement of the at least two proof masses constrained to rotate about a X-direction.

10. The accelerometer of claim 1 which includes a self-test electrode to actuate the at least one proof mass for test purposes.

11. The accelerometer of claim 1 which includes travel stoppers in at least one of an X or a Y or Z direction.

12. The accelerometer of claim 1 wherein the at least one proof mass is connected electrically to the sense substrate at an anchor.

13. The accelerometer of claim 1 wherein the at least one proof mass is connected electrically to the sense substrate through the at least one flexure.

14. The accelerometer of claim 1 wherein the sense substrate comprises a single crystal silicon wafer.

15. The accelerometer of claim 1 wherein the sense substrate comprises a CMOS integrated circuit.

16. The accelerometer of claim 15 wherein a measurement is provided utilizing a half bridge configuration with a capacitance being in series with a constant capacitance.

17. The accelerometer of claim 15 wherein a measurement is provided utilizing a full bridge configuration with a capacitance being with three other capacitances.

18. The accelerometer of claim 16 wherein a capacitance measurement for the half bridge configuration is proof mass driven.

19. The accelerometer of claim 16 wherein a capacitance measurement for the half bridge configuration is electrode driven.

20. The accelerometer of claim 17 wherein a capacitance measurement for the full bridge configuration is proof mass driven.

21. The accelerometer of claim 17 wherein a capacitance measurement for the full bridge configuration is electrode driven.

Referenced Cited
U.S. Patent Documents
4510802 April 16, 1985 Peters
4601206 July 22, 1986 Watson
4736629 April 12, 1988 Cole
4783742 November 8, 1988 Peters
4841773 June 27, 1989 Stewart
5251484 October 12, 1993 Mastache
5349858 September 27, 1994 Yagi et al.
5359893 November 1, 1994 Dunn
5367631 November 22, 1994 Levy
5415040 May 16, 1995 Nottmeyer
5433110 July 18, 1995 Gertz et al.
5440326 August 8, 1995 Quinn
5444639 August 22, 1995 White
5511419 April 30, 1996 Dunn
5541860 July 30, 1996 Takei et al.
5574221 November 12, 1996 Park et al.
5629988 May 13, 1997 Burt et al.
5635638 June 3, 1997 Geen
5698784 December 16, 1997 Hotelling
5703293 December 30, 1997 Zabler et al.
5703623 December 30, 1997 Hall et al.
5734373 March 31, 1998 Rosenberg et al.
5780740 July 14, 1998 Lee et al.
5825350 October 20, 1998 Case, Jr.
5895850 April 20, 1999 Buestgens
5898421 April 27, 1999 Quinn
5955668 September 21, 1999 Hsu et al.
5992233 November 30, 1999 Clark
5996409 December 7, 1999 Funk et al.
6067858 May 30, 2000 Clark et al.
6122961 September 26, 2000 Geen et al.
6134961 October 24, 2000 Touge et al.
6158280 December 12, 2000 Nonomura et al.
6189381 February 20, 2001 Huang et al.
6230564 May 15, 2001 Matsunaga et al.
6250156 June 26, 2001 Seshia et al.
6250157 June 26, 2001 Touge
6269254 July 31, 2001 Mathis
6279043 August 21, 2001 Hayward et al.
6292170 September 18, 2001 Chang et al.
6343349 January 29, 2002 Braun et al.
6370937 April 16, 2002 Hsu
6374255 April 16, 2002 Peurach et al.
6386033 May 14, 2002 Negoro
6391673 May 21, 2002 Ha et al.
6393914 May 28, 2002 Zarabadi et al.
6424356 July 23, 2002 Chang et al.
6429895 August 6, 2002 Onuki
6430998 August 13, 2002 Kawai et al.
6480320 November 12, 2002 Nasiri
6481283 November 19, 2002 Cardarelli
6481284 November 19, 2002 Geen et al.
6481285 November 19, 2002 Shkel et al.
6487369 November 26, 2002 Sato
6487908 December 3, 2002 Geen et al.
6494096 December 17, 2002 Sakai et al.
6508122 January 21, 2003 McCall et al.
6508125 January 21, 2003 Otani
6513380 February 4, 2003 Reeds, III et al.
6520017 February 18, 2003 Schoefthaler et al.
6533947 March 18, 2003 Nasiri et al.
6573883 June 3, 2003 Bartlett
6636521 October 21, 2003 Giulianelli
6646289 November 11, 2003 Badehi
6668614 December 30, 2003 Itakura
6720994 April 13, 2004 Grottodden et al.
6725719 April 27, 2004 Cardarelli
6758093 July 6, 2004 Tang et al.
6794272 September 21, 2004 Turner et al.
6796178 September 28, 2004 Jeong et al.
6823733 November 30, 2004 Ichinose
6834249 December 21, 2004 Orchard
6845669 January 25, 2005 Acar et al.
6848304 February 1, 2005 Geen
6859751 February 22, 2005 Cardarelli
6860150 March 1, 2005 Cho
6892575 May 17, 2005 Nasiri et al.
6915693 July 12, 2005 Kim et al.
6918297 July 19, 2005 MacGugan
6918298 July 19, 2005 Park
6938484 September 6, 2005 Najafi et al.
6939473 September 6, 2005 Nasiri et al.
6955086 October 18, 2005 Yoshikawa et al.
6963345 November 8, 2005 Boyd et al.
6972480 December 6, 2005 Zilber et al.
6981416 January 3, 2006 Chen et al.
7004025 February 28, 2006 Tamura
7028546 April 18, 2006 Hoshal
7028547 April 18, 2006 Shiratori et al.
7036372 May 2, 2006 Chojnacki et al.
7040163 May 9, 2006 Shcheglov et al.
7040922 May 9, 2006 Harney et al.
7057645 June 6, 2006 Hara et al.
7077007 July 18, 2006 Rich et al.
7104129 September 12, 2006 Nasiri et al.
7121141 October 17, 2006 McNeil
7154477 December 26, 2006 Hotelling et al.
7155975 January 2, 2007 Mitani et al.
7158118 January 2, 2007 Liberty
7159442 January 9, 2007 Jean
7168317 January 30, 2007 Chen
7180500 February 20, 2007 Marvit et al.
7196404 March 27, 2007 Schirmer et al.
7210351 May 1, 2007 Lo et al.
7222533 May 29, 2007 Mao et al.
7236156 June 26, 2007 Liberty et al.
7237437 July 3, 2007 Fedora
7239301 July 3, 2007 Liberty et al.
7240552 July 10, 2007 Acar et al.
7243561 July 17, 2007 Ishigami et al.
7247246 July 24, 2007 Nasiri et al.
7250112 July 31, 2007 Nasiri et al.
7258011 August 21, 2007 Nasiri et al.
7260789 August 21, 2007 Hunleth et al.
7262760 August 28, 2007 Liberty
7284430 October 23, 2007 Acar et al.
7289898 October 30, 2007 Hong et al.
7290435 November 6, 2007 Seeger et al.
7299695 November 27, 2007 Tanaka et al.
7325454 February 5, 2008 Saito et al.
7331212 February 19, 2008 Manlove et al.
7333087 February 19, 2008 Soh et al.
7352567 April 1, 2008 Hotelling et al.
7377167 May 27, 2008 Acar et al.
7386806 June 10, 2008 Wroblewski
7395181 July 1, 2008 Foxlin
7414611 August 19, 2008 Liberty
7424213 September 9, 2008 Imada
7437931 October 21, 2008 Dwyer et al.
7442570 October 28, 2008 Nasiri et al.
7458263 December 2, 2008 Nasiri et al.
7508384 March 24, 2009 Zhang et al.
7522947 April 21, 2009 Tsuda
7533569 May 19, 2009 Sheynblat
7549335 June 23, 2009 Inoue et al.
7552636 June 30, 2009 Datskos
7617728 November 17, 2009 Cardarelli
7621183 November 24, 2009 Seeger et al.
7677099 March 16, 2010 Nasiri et al.
7677100 March 16, 2010 Konaka
7779689 August 24, 2010 Li et al.
7783392 August 24, 2010 Oikawa
7784344 August 31, 2010 Pavelescu et al.
20020189351 December 19, 2002 Reeds et al.
20030159511 August 28, 2003 Zarabadi et al.
20040066981 April 8, 2004 Li et al.
20040160525 August 19, 2004 Kingetsu et al.
20040179108 September 16, 2004 Sorek et al.
20050066728 March 31, 2005 Chojnacki
20050110778 May 26, 2005 Ben Ayed
20050212751 September 29, 2005 Marvit et al.
20060017837 January 26, 2006 Sorek et al.
20060032308 February 16, 2006 Acar et al.
20060033823 February 16, 2006 Okamura
20060061545 March 23, 2006 Hughes et al.
20060115297 June 1, 2006 Nakamaru
20060119710 June 8, 2006 Ben-Ezra et al.
20060139327 June 29, 2006 Dawson et al.
20060164382 July 27, 2006 Kulas et al.
20060164385 July 27, 2006 Smith et al.
20060185502 August 24, 2006 Nishitani et al.
20060187308 August 24, 2006 Lim et al.
20060251410 November 9, 2006 Trutna, Jr.
20070035630 February 15, 2007 Lindenstruth et al.
20070063985 March 22, 2007 Yamazaki et al.
20070113207 May 17, 2007 Gritton
20070146325 June 28, 2007 Poston et al.
20070167199 July 19, 2007 Kang
20070176898 August 2, 2007 Suh
20080009348 January 10, 2008 Zalewski et al.
20080088602 April 17, 2008 Hotelling
20080098315 April 24, 2008 Chou et al.
20080134784 June 12, 2008 Jeng et al.
20080158154 July 3, 2008 Liberty et al.
20080204566 August 28, 2008 Yamazaki et al.
20080314147 December 25, 2008 Nasiri et al.
20090088204 April 2, 2009 Culbert et al.
20100013814 January 21, 2010 Jarczyk
Foreign Patent Documents
0429391 August 1995 EP
Other references
  • Oboe, R., Lasalandra, E., White, M. M. MEMS-based Accelerometers and their Application to Vibration Suppression in Hard Disk Drives. MEMS/NEMS Handbook Techniques and Applications vol. 4, Springer 2006, pp. 1-29 see pp. 7-22.
  • Singh, Amit, “The Apple Motion Sensor as a Human Interface Device,” www.kernelthread.com, 1994-2006.
  • Cho, et al., Dynamics of Tilt-based Browsing on Mobile Devices. CHI 2007, Apr. 28-May 3, 2007, San Jose, California, USA., pp. 1947-1952.
Patent History
Patent number: 7934423
Type: Grant
Filed: Dec 10, 2007
Date of Patent: May 3, 2011
Patent Publication Number: 20090145225
Assignee: Invensense, Inc. (Sunnyvale, CA)
Inventors: Steven S. Nasiri (Saratoga, CA), Goksen G. Yaralioglu (Mountain View, CA), Joseph Seeger (Menlo Park, CA), Babak Taheri (San Francisco, CA)
Primary Examiner: Helen C. Kwok
Attorney: Sawyer Law Group, P.C.
Application Number: 11/953,762
Classifications
Current U.S. Class: Angular Acceleration (73/514.02); Capacitive Sensor (73/514.32)
International Classification: G01P 15/08 (20060101); G01P 15/125 (20060101);